C++. There is a compilation error when building. Can anyone tell me what is going on?

Question

https://sololearn.com/compiler-playground/c7BBMeQMz5T8/?ref=app

Answer 1

It's a warning saying that you're using 2 different types with each other.

int can be positive or negative (signed) and is usually 4 bytes
sizeof operator cannot be negative (long unsigned int) and long can be 4-8 bytes

the code will work, but you may encounter over or underflow, which is why it's a warning